Simple event bus

event-bus.js

const EventBusFactory = () => {
  let repo = {};
  return {
    add(key, fn){
      if(typeof fn !== 'function') throw `Invalid parameter. Second parameter must be a function.`;
      if(!repo[key]) repo[key] = [];
      if(!repo[key].includes(fn)) repo[key].push(fn);
    },
    remove(key, fn){
      if(!repo[key]) return;
      if(!repo[key].includes(fn)) return;
      const index = repo[key].indexOf(fn);
      if(index !== -1) repo[key].splice(index, 1);
    },
    trigger(key, data){
      if(!repo[key]) return;
      repo[key].forEach(fn => fn(data));
    }
  }
}